Such a method is known from DE-AS 1 114 719. This publication refers to a method for hot filling carbonated beverages, particularly beer. The beverage is here filled via a device comprising a valve-controlled filling element with an outlet opening through which the liquid passes into the container. There is also provided a return gas path in the form of a return gas tube that extends through the valve up into the container and through which the air displaced by the liquid can escape out of the container. Such return gas tubes also define the filling level in the container. Here liquid and possibly formed foam cannot be prevented from wetting the return gas tube on the outside and inside and from possibly getting stuck there. In a renewed filling process for a further container the foam stuck in the interior of the return gas tube and evolving from the preceding filling operation may for instance interfere with the new filling operation, i.e. for instance it may prolong the filling time, reduce the filling level or create an excessive amount of foam due to interference with the pressure relief in a clogged return gas tube. In the known method, the return gas tube is therefore spray-washed or blown out as a precautionary measure after each filling operation, so that liquid residues possibly contained in the return gas tube pass to the outside.
Blowing or spray-washing, however, constitutes an additional operation that needs time, whereby the filling operation is prolonged. Moreover, the cleaning agent is consumed. If water is used as the cleaning agent, it must be collected and discharged in addition. The return gas tube is blown out with inert gas, i.e. for instance CO2, which passes into the atmosphere after blowing and is lost. Although the individual blow-off process requires a very small amount of gas, gas consumption will add up considerably due to the many blow-off processes.